A conventional general ultrasonic diagnostic apparatusic diagnostic apparatus includes ultrasonic wave transmitting/receiving means for transmitting and receiving ultrasonic waves to/from an object, ultrasonic wave transmission/reception control means for controlling transmission/reception of ultrasonic waves, cross-sectional scanning means for repetitively obtaining tomogram data in the object containing a motional tissue at a predetermined period by using a reflection echo signal from the ultrasonic wave receiving means, and image display means for displaying time-series tomogram data obtained by the cross-sectional scanning means. The structure of the biomedical tissue in the object is displayed as a B mode image, for example.
Furthermore, an ultrasonic diagnostic apparatusic diagnostic apparatus that can obtain and display elasticity data of an object's tissue has been recently developed (for example, patent document 1). According to the ultrasonic diagnostic apparatusic diagnostic apparatus as described above, external force is applied from the body surface of an object to an ultrasonic wave transmitting/receiving face of an ultrasonic probe by a manual method to press a biomedical tissue, and displacement of each point is measured by using a correlation calculation of ultrasonic wave reception signals of two frames which are adjacent to each other in time series (continuous two frames). This displacement is spatially differentiated to measure distortion, and the data of the distortion is imaged. Furthermore, elasticity modulus data of the biomedical tissue represented by Young's modulus or the like are imaged from the stress distribution caused by the external force and the distortion data. The hardness or softness of the biomedical tissue can be displayed with an elasticity image based on the distortion data and the elasticity modulus data (hereinafter referred to as elasticity frame data) as described above.
The technique of obtaining the elasticity image described above has been expected to be applied to not only diagnosis of tumor mass type lesion such as cancer or the like, but also diagnosis of diffuse disorder. In the case of a structure that local indurated tissues such as knot or the like are scattered in a surrounding soft tissue in diffuse disorder, an elasticity image obtained by applying the above technique has a dapple pattern which reflects an inhomogeneous structure. When a disorder proceeds, for example, from hepatitis to cirrhosis and thus fibrosis proceeds, the knot expands into the liver parenchyma and the dapple pattern of the elasticity image is complicated. An examiner can estimate a progress state of a disorder on the basis of the state of the dapple pattern.
Patent Document 1: JP-A-5-317313